Magnetic transducer adapted to compensate for twisting of the record wire



May 24, 1949. H E. TOMPKINS MAGNETIC TRANS DUGER ADAPTED T0 COMPENSATEFOR TWISTING OF THE RECORD WIRE Filed Sept. 6, 1945 5 Sheets-Sheet 1Fig. 2 /0 INVENTOR. HOWARD E. TOMPK/NS ATTORNEYS y 1949- H. E. TOMPKINS2,471,251

MAGNETIC TRANSDUCER ADAPTED TO COMPENSATE FOR TWISTING' OF THE RECORDWIRE Filed Sept. 6, 1945 3 Sheets-Sheet 3 v INVENTOR.

' HOWARD E. TOMPK/NS A TTORNEVS Patented May 24, 1949 MAGNETICTRANSDUCER ADAPTED TO COMPENSATE FOR TWISTING OF THE RECORD WIRE HowardE. Tompkins, Media, Pa., assignor, by mesne assignments, to PhilcoCorporation, Philadelphia, Pa, a corporation of Pennsylvania ApplicationSeptember 6, 1945, Serial No. 614,739

18 Claims. 1

This invention relates to a magnetic wire recorder, and morespecifically it relates to a system for reproducing transverselymagnetized recordings upon a round wire in such a manner that thereproduced signals are unaffected by twistin of the wire on thelongitudinal axis.

In recording intelligence upon a round wire by the transverse method ofmagnetization, a difiiculty is encountered in the reproduction of thesound or other intelligence from the record on the wire because of thecircular cross-section of the wire. This circular cross-section makes itpossible for the wire to twist upon its longitudinal axis.

Consequently it is possible during reproduction for the wire to twist tosuch an extent that the magnetization of the wire is at right angles tothe pick-up coil of the reproducer. Under these circumstances, theamplitude of the signal picked up may vary from full signal at no twistto no signal at a 90 twist of the wire.

Various arrangements have been suggested for overcoming such adifliculty. One such arrangement involves the use of automatic volumecontrol in the amplifier, but this automatic volume control ceases tofunction when the wire has rotated a full 90 from the pick-up coil.

Another method which has been suggested for overcoming this difiicultyemploys an automatic follow-up system whereby the pick-up coils arecaused to rotate around the longitudinal axis of the wire in synchronismwith the twisting of the wire. Such a mechanism, while accomplishing thedesired result. is subject to high maintenance cost and possiblefailure,

In my invention I use two pick-up magnetic structures oriented at rightangles with respect to one another and at substantially the samelocation longitudinally on the wire which is to be run through thereproducer. The use of two such coils at right angles to each otherinsures that there always will be a signal available from the wire forif in one coil there is zero signal because the magnetism of the wire isoriented at right angles to the pick-up axis of the coil, then the othercoil will receive a full signal.

In order to obtain an output from these two pick-up heads, it isnecessary to find a method of combining the two voltages in such amanner that the combined signal will be substantially independent of theorientation of the magnetic axis within the pick-up head structure. Itcan be shown that a simple addition of these two voltages will notsufiioe since under certain circumstances, with these two voltages addedtogetherdirectly, there will be a cancellation between the two and nosignal will result from their combination.

I have discovered that in order to combine these two signals properly,one of the signals should be shifted in phase by with respect to theother one. When this is done, the two resultant signals can be addedtogether vectorially and their sum does not contain the orientationangle of the magnetic axis of the wire in such a way as to vary theamplitude of the signal obtained.

This means that regardless of the orientation of the wire, the outputfrom the system has a constant amplitude if the magnetization of thewire is constant in amplitude. In other words, as the amplitude ofmagnetization of the wire varies, the output amplitude varies in thesame proportion independently of the orientation of themagnetic axis ofthe wire on which the record has been recorded,

Consequently, an object of my invention is to provide a means forreproducing transversemagnetization upon a round wire in such a mannerthat there will be no interference or distortion resulting from randomorientation of the magnetic axis of the wire.

Another object of my invention is to provide means for cancelling outthe effect of twisting of a round wire in a magnetic recording.

Other objects of my invention will become apparent upon a study of thediagrams, in which Figure 1 represents a schematic diagram of my pick-uphead.

Figure 2 represents certain vector diagrams used in explaining theaction of Figure 1.

Figure 3 is a block diagram of my invention.

Figure 4 represents phase shift curves obtained from the apparatus ofFigure 3; and

Figure 5 is a detailed circuit diagram of the apparatus used to obtainthe phase shift curves of Figure 4 and used in conjunction with myreproducing mechanism.

Referring now to Figure 1, the wire I0! is shown in cross-section. It isconsidered to be a long, thin, round wire whose length is perpendicularto the plane of the drawing, In order to explain the operation of thisdevice, the wire is represented as having magnetic poles impressed uponit, the north pole being represented by the reference letter N and thesouth pole being 5 represented by the reference letter S.

The magnetic axis of the magnetic force impressed on the wire by therecording mechanism is at an angle 0 with respect to a horizontalreference axis. The strength of these magnetic poles varies as theposition is changed longitudinally along". the'wireand' it isthe'variationin the strength of-these magnetic poles which constitutesthe recording upon the wire. The recording mechanism, which may be ofany well known construction, is arranged toimpress. upon the. wirevariations in magnetic pole strength inaccordance with desired signalrecording.

The object of my invention is to satisfactorily reproduce the variationsin magnetic pole strength ranged at such an angle as to carry flux-fromthe 5- permanent magnetism of th wire IIlI in the horizontal directionand -magnetic structure I83" is? similarly arranged: to: carry flux fromthe per; manent :magnetism in the vertical directions Each-1 of" thesetwo magnetic structures is wound-, with a= pick up coil; structure IElZbeing' wound :with -pick upcoil IM and structure" I03being=;wound-with-pick-up coil I05; Variations in the magnetization ofthe wire lIlI cause varia l tionsiinzthe flux-inthe pick-up magneticstructunes I02.v and I03. and these' variations in'flux through .coils-I04 and I05 induce voltages inv thesercoilsr. Inworder to more fullyunderstand the operationof my, invention, I have labeled thesetwovoltages: as-E1 and E2.

In Figure 2w, thereis showna simple construction-lion obtain-ing themagni-tude of these two voltagesEiandfEa Theangle a-is'plotted, as isindicated linathis diagram; andwa-line for vectorIUBr-isrdraWn'.at-this' angle with respect to the" horizontal- Vectorlilfi has a length-whieh is" proportional to: :the": voltage: whichwould be in troducedfiin-one oiathe1pick up coils-if it wereoriented-:to 'be -parallelto the magneticaxis of thecwirev- Thatis,-if-eitherone"of the'two'pickan up coils were rotated so that thenorthand south" poles sof the--magnetization on the wire were-directly:opposite the I polepieces" of the magnetic structures;the -voltagespicked up? in the coils wouldb'eproportional 'to the vector I 56.

In.Fig-; 1,,however, this arrangement is not carried out, andconsequently thevoltages induceddn thetwdwindi'ngsare proportional tocertaimfunctionspfthe angle 0.- In particular, the voltage induced-inthe winding IIl l'is the m maximum. voltage" multiplied by the cosine ofanglefios correspondingly, the voltage induced in coil IIl5 is :themaximum possible induced voltage multiplied by the sine 0. Theconstruction of Figure 2' carries out this multiplication:

The magnitudepf Ei', represented by vector IIlI, is showrr'asthe'verticalprojection of vector I06 andxthecmagnitude of E2-is shown asthehorizontal projection I 08 of'vector Hi6;-

Itiis to-befu-nderstood that these two vectors llt'bandlflfl are-riotvectors in the sense that they represent vector quantities oi E1 and E2.Their lengths only are associated with E1 and The anglesrinvolved aredrawn from the angles onorientationro zthe magnetic structure and wire,

and consequently the angles in Figure 2a correspond to angles in themechanical structure and not to electrical angles.

In fact, the two voltages E1 and E2 are in phase with each other, andconsequently when they are added together in Figure 2b, the directaddition of these two voltages E1 and E2 is shown. Here the totalvoltage is the sum of the two voltages and since both E1 and E2 are inphase with each other, the vectors representing E1 and E2 are drawn asco-linear vectors.

As":the'-'ang1e"-0"is varied; the two projections IilI and mIi sh'own'in Figure-2a will vary in size. It can be shown that as these two vary,the sum oiFthe two as shown in Figure 212 will also vary in .size.. In.particular, if the angle 0 should vary betweenQD and 180, it will beobserved that the voltage-E2'willube reversed in phase. As a result, inFigure 21), E2 would turn out to be oppositexir rdirectionto E1 and whenthe angle 0 became'fi the amplitude of E2 would equal the amplitudeof'Er. Under this circumstance, thertwewouldcanceland the sum ofvoltages E1 and E2 would then be zero. This would not be asatisfactory'system for reproducing the recording on the wire; it wouldbe no better than the use of?a single' piclr-up coil.

In my-invention l Fuse electrical means -to asso ciate the amplitudes E1andE2 with the-angle 0' g in the same manner that the diagram-of Figure227, associates the two amplitudes and obtains therefrom the vector I06.otm-y invention is shown-in Figure 2'0. According to my inventionflcause vector E1 to be shifted in phase from vector E2 by In'carrying outthis-process, both vectors may he -shifted inphase; but vector E1 isshiitediin- Consequently, in

phase 90 more than vector E2. Figure:2c,=the--vector-E1 after its phaseshift, is

represented by vector )9. This vector is called Similarly, vectorIIO-'"represents voltage E2.

Er; after having-been-shifted by the phase angle. This vector" I I Wisused to represent the voltage which-is voltage'E2 after its phase shift.The characteristics of the phase shift given to the two-voltages, causeE1 and E2 to be out of accordingly with the result that Figure 2c al--ways bears an essential similarity-to Figure 2a. Consequently, vectorIII remains at a constant length-fora constant input amplitude independ-Infact, theangle entof the phase angle of 0. I IZin' Figure. 2c isalways the same'as angle 0 1 in'Figure 2a.

A' block diagram ofthe apparatus used in ace complishing'my, inventionis showniniFigure- 3.

Here, pick-up .coils I05andv I04 feed voltages .Er and-E2-into phaseshifters H2 and 3.. Phasetorially and: fed into theamplifier. I14, whichin The vector'diagram" Likewise, the.

Phase turn feeds the loud-speaker H5. This loudspeaker is symbolic ofany reproducing device which may be desired. Thus, in order to morethoroughly explain the action of my invention, I will make reference tocertain equations, numbered 1 to 10, which follow in the descriptionbelow.

Let the magnetization in the wire be represented by Equation 1.

This equation can be thought of as the flux which would pass through oneof the pick-up structures if the wire were so oriented that the maximumflux passed through this pick-up structure. The time variationrepresented by sine of is obtained by the longitudinal motion of thewire through the pick-up structure. In view of the random orientation ofthe wire, each of the pick-up coils will receive flux proportional tothe appropriate functions of the angle 9. These two fluxes are indicatedas 1 and 4m in Equations 2 and 3.

1= m sin of sin 6 (2) These are the fluxes which pass through themagnetic structures I02 and E03. From these fluxes, voltages are inducedin the coils I04 and 105. Thus, in coil [05, the voltage induced is E1given by Equation 4 and in coil I04, the voltage induced is E2 as givenby Equation 5. In these equations, N is the number of turns in eachcoil, assuming them to be identical.

As has been mentioned before, the summation of these voltages directlyis not useful in reproduction of the signals on wire 50!. This is shownby Equation 6 in which is given the sum of E1 and E2.

The last term in this equation, that is, the sine of (+45) is obtainedby mathematical processes from the appropriate Equations 4 and that is,the sum of sine 6 and cosine 0. It is recognized in mat..ematics thatthis function, sine of (04-45"), varies between 0 and I depending uponthe value of 0. Consequently, for specified values of 6, this functionwill be Zero and no output voltage would result. This makes such asystem of direct combination of the two coils totally impractical.

The output voltages of my phase shifters, however, do make a practicalsystem. These output voltages are given in Equations 7 and 8.

If E1 is the voltage as shifted by phase shifter H3, and E2 is thevoltage as shifted by phase shifter H2, it is to be observed that thephase shifters cause the addition of the term cc and oz90 in thefunctions involving wt in these two equations.

With my invention, these two voltages E1 and E2 are added together. Inorder to make these two additions easy, it is first to be observed thatthe cosine curve involving of, Equation 8, is equivalent to a sine curveas is shown by Equation 9, which is an identity taken from trigonometry.

6 Consequently, the sum of E1" and E2, as given by Equation 10 is in aform which is recognized in trigonometry as being the expanded form ofthe sine of the sum of two angles.

When this Equation 10 is collected into a more concise form bytrigonometric transformation, Equation 11 results, in which the sum ofthe two angles E1 and E2 is given as the sine of wia+6.

Inspection of this equation reveals that the angle 0 enters in theequation only as a phase angle in the resultant voltages. It does notappear in such a way as to alter the amplitude of the resultant voltage.This is precisely the effect which I desired to obtain when I made myinvention. It makes the invention a satisfactory one for reproducingsound from a recording made transversely on a round wire since the ear,which will be the ultimate interpreter of the reproduced sound, does notrespond to variations in phase angle of a signal. Thus the inclusion of0 as a phase angle is unimportant in this system and will not causedistortion as far as the ear is concerned.

In another form of my invention I use a plurality of pick-up coils and aplurality of phase shifting networks so arranged that the phase shiftsof the networks are correlated with the angular positions of the pick-upcoils. For example, three pick-up coils arranged spatially at 60intervals and three phase shifters designed for 60 phase angledifferences provide an output independent of the twist of the wire.

Still another variation of my invention uses in place of the pluralityof magnetic structures, a single magnetic structure built and wound in amanner similar to that employed in the construction of polyphase motorstators.

My invention has been described, heretofore, with respect to a singlefrequency of magnetization. However, it is well known that ordinarysound to be reproduced will be composed of a great number offrequencies. From the wellknown principle of superposition, it will befound that a complicated sound may be considered to be made up of asummation of individual frequencies. Since the entire system heredescribed is a linear system, the system will behave, in regard to eachfrequency component, just as it would behave with regard to thatfrequency independently of the presence of other frequencies.

In consequence of this, the output signal of the system will contain agreat number of frequencies each being shifted by the phase angle 0 andin addition, each being shifted by the phase angle minus a. Inaccordance with my invention, the phase angle a is different for eachfrequency and consequently each frequency component in the output willbe shifted in phase from the corresponding frequency component in theinput by a specified amount, which will be different from the phaseshift for each other frequency component. This, however causes nodifficulty since the ear is unresponsive to changes in the phase angle.

In order to accomplish the phase shift of between the two signals E1 andE2, the phase shifters H2 and H3 are designed in accordance with myinvention as described in my co-pending patent application, Serial No.613,457, filed August 30, 1945. I

Inaccordance withsthis invention, I obtain a' phase shift curveeforphaseshifter H3 in accordance with curvershown' in Figure 4. Likewise, withrespect-to. phase shifter H2, I obtain a .phase shift in accordance.with the curve of Figure 4.

It is to be observed that these two curves indicate a changingwphaseshift with respect to frequency over the-whole frequency band, but thatthe essential characteristics of these two curves are that thephaseanglediffers between the two systems substantially 90 over the audiofrequency band. This is shown as curve 24 which is the difference inphase between the two systems.

For theoretically perfect operation, this phase difference should beexactly 90. However, if the phase angle Variesby slight differences from90, there will be only aslight variation in the resultant amplitude,which will result in only Slight variations in the output amplitude asangle varies. Inconsequence of this, the difference in phase shiftbetween phase shifter H2 and phase shifter ll3l= need not be exactly 90but may be between a range of approximately degrees of 90;

Thus, the network whose curves are shown in Figure 4, accomplishes thissatisfactorily. This network which gives the curves shown in Figure 4 isshown in Figure'5i This shows a complete reproducing system, with.pick-up coils, phaseshifting networks forcombining the two signals,amplifier, and reproducing speaker.

In Figure 5, ML energizes the two pick-up coils I04 and W5: One. ofthesepick-up coils is fed into the top-channel consisting of two bridgecircuits 33 and 34, and1a differential amplifier comprising vacuum: tube39; the output of which feeds into a differential" amplifier composed oftubes 3| and 32;

The other pick-upcoil feeds into the lower channel which is composed ofphase shifting bridges 36 and 31 and" a differential amplifier composedof tube 4|, the-output of which feeds into the differential amplifiercomposed of tubes 3| and 32;

These phase shiftin channels are built in accordance with my inventiondescribed in copending application Serial No. 613,457, filed August 30,1945. In the lower channel, for example, bridge 36 has a predeterminedphase shift characteristic with respect to frequency. Bridge 31 has asimilar, but different phase shift characteristic with respect tofrequency; that is, its phase shift characteristic has a point ofinflection at a different-frequency than does bridge Since the two ofthese bridge networks are eifectively connectedin tandem in thiscircuit, their phase characteristics are additive. Consequently, thephase characteristic of the lower channel consisting of bridge 35 andbridge 31 together, is the sum of the individual phase characteristic ofthe two networks.

Such a curve is given, for example, by curve 20 in Figure 4. This curveis almost linear with respect to th logarithm of the frequency. Theupper channel is soproportioned that it has the same type of curveforits phaseshift curve, but it has this curve shifted in frequency to ahigher frequency.

Accordingly, the .curve of theupper channel in Figure 5 is shownhmFigure 4 as curve 23. This is accomplished in theediagram byusingsmaller RC products-in the upper; channel thanare used,

RC product in bridge 33has a lower value than the RC product in bridge36 and the RC' product" in bridge 34 has a lower value than the RCproductin bridge 31.

cycles is 5.3 approximately. This, then, is the ratio of the frequenciesof the two curves. Consequently R1C1=5.3R2C2.

This ratio, of course, does not apply to capacitors such as 38, whichare merely blocking capacitors and do not function in providing thephase shift in these networks. only to those capacitors in the bridgecircuits themselves. The output circuit of Figure 5 is a conventionalpush-pull connection with a transformer and a loud-speaker connectedinto the secondary of the transformer.

In the description and specification which I have given for my inventionabove, I have described it with respect to a specific network. However,I do not wish it to be limited to a specific network; but instead, Iprefer to have my invention described by the following claims.

I claim:

1. In a system for reproducing sound from a magnetized wire which issubject to arbitrary twists, two pick-up coils at substantially the samelocation longitudinally on the wire and arranged to be responsive tomutually perpendicular components of magnetic flux from said wire, theamplitude of the induced signals in said coils varying in accordancewith said twists, two phaseshifting networks, one of said phase-shiftingnetworks being fed from one of said pick-up coils and the other of. saidphase-shifting. networks being fed from the other of said pick-up coils,said phase-shifting networks having phase characteristics which differfrom each other by substantially over a band of frequencies, and meansfor combining the output signals of said phase-shifting networks toproduce a resultant signal which varies in amplitude in accordance withthe magnetic recording on said wire and independent of any twistthereof.

2. In a system for the reproduction of sound from signals transverselyrecorded on a magnetized wire, two pick-up devices, each including amagnetic circuit and a coil linking said magnetic circuit, said pickupsystems being oriented to be responsive to magnetization at the samelongitudinal location on said wire butto be responsive to mutuallyperpendicular components of magnetic flux set up by the magnetization ofsaid wire, two phase-shifting networks, each having input and outputterminals, the input terminals of one of said phase-shifting networksbeing connected to one of said pick-up devices, and the input terminalsof the other of said phase-shifting networks being connected to theother of said pick-up devices, the output terminals of saidphase-shifting networks being connected so as to provide a signal whichis the sum of the output signals of said phase-shifting networks, andsaid phase-shifting networks havin phase-shift characteristics whichdiffer from each other by substantially 90.

3. In a systemfor. reproducing-sound from a For all of these RCproducts. the same ratio exists.

This ratio applies magnetized wire of circular cross-section which issubject to arbitrary twists, pick-up coil means arranged to beresponsive to magnetic flux from said wire at substantially the samelocation longitudinally on the wire, means including circuit connectionsto said pick-up coil means for producing from said flux two signals, oneof the signals being shifted in phase substantially 90 with respect tothe other, and means including circuit connections to said last circuitconnection means for vectorially adding the resultant signals to producea signal which is varied in accordance with the magnetization of saidWire and independent of the orientation angle of the magne ism of thewire.

4. The method of reproducing sound from a magnetized wire which issubject to arbitrary twists, comprising generating two components fromsaid flux, producing therefrom two signals, one of the signals beingshifted substantially 90 with respect to the other, and adding the twosignals vectorially.

5. In a system for reproducing sound from a magnetized wire of circularcross-section which is subject to arbitrary twists, pick-up coil meansarranged to be responsive to magnetic flux from said wire at the samelongitudinal location of said wire, means including circuit connectionsto said pick-up coil means for producing from said flux two signals, oneof the signals being shifted in phase substantially 90 with respect tothe other over a predetermined frequency range, and means includingcircuit connections to said last circuit connection means forvectorially adding the resultant signals to produce a signal which isvaried in accordance with the magnetization of said wire and independentof the orientation angle of the magnetism of the wire.

6. The method of reproducing sound from a magnetized wire which issubject to arbitrary twists, comprising generating two components fromsaid flux, producing therefrom two signals, one of the signals beingshifted substantially 90 with respect to the other over a predeterminedfrequency range, and adding the two signals vectorially.

'7. In a system for reproducing sound from a magnetized wire which issubject to arbitrary twists, two pick-up coils at right angles to eachother at substantially the same location longitudinally on the wire andarranged to be responsive to component magnetic flux from said wire,means including circuit connections to said pick-up coils for producingfrom said flux two signals, one of the signals being shifted in phasesubstantially 90 with respect to the other, and means including circuitconnections to said last circuit connection means for vectorially addingthe resultant signals to produce a signal which is varied in accordancewith the magnetization of said wire and independent of the orientationangle of the magnetism of the wire.

8. In a system for reproducing sound from a magnetized wire of circularcross-section which is subject to arbitrary twists, a pair of magneticstructures at substantially the same location longitudinally on the wireand one of said structures being arranged to pick up flux from said wirein the horizontal direction, and the other of said structures beingarranged to pick up flux from said wire in the vertical direction, acoil wound in each of said structures and energized by the flux therein,a circuit connected to each of said coils, the signals in each of saidcircuits being substantially 90 in phase displacement 10 from eachother, and a common circuit connected to the output of each of saidfirst-mentioned circuits.

9. In a system for reproducing sound from a magnetized wire which issubject to arbitrary twists, a pair of magnetic structures atsubstantially the same location longitudinally on the wire and one ofsaid structures being arranged to pick up flux from said wire in thehorizontal direction, and the other of said structures being arranged topick up flux from said wire in the vertical direction, a coil wound ineach of said structures and energized by the flux therein, and means forgenerating a signal equal to the square root of the sum of the squaresof the signals induced in each of said coils.

10. In a system for reproducing sound from a magnetized wire which issubject to arbitrary twists, two pick-up coils at substantially the samelocation longitudinally on the wire and arranged to be responsive topredetermined components of magnetic iiux from said wire, the amplitudeof the induced signals in said coils varying in accordance with saidtwists, two phase-shifting networks, one of said phase-shifting networksbeing fed from one of said pick-up coils and the other of saidphase-shifting networks being fed from the other of said pick-up coils,said phaseshiftin networks having phase characteristics which differfrom each other by said predetermined angle over a band of frequencies,and means for combining the output signals of said phase-shiitingnetworks to produce a resultant signal which varies in amplitude inaccordance with the magnetic recording on said wire and independent ofany twist thereof.

11. In a system for the reproduction of sound from signals transverselyrecorded on a magnetized wire of circular cross-section, two pick-updevices at substantially the same location longitudinally on the wireand each including a magnetic circuit and a coil linking said magneticcircuit, said pick-up systems being oriented to be responsive tomagnetization at the same longitudinal location on said wire but to beresponsive to predetermined components of magnetic flux set up by themagnetization of said wire, two phase-shifting networks, each havinginput and output terminals, the input terminals of one of saidphase-shifting networks being connected to one of said pick-up devices,and the input terminals of the other of said phase-shifting networksbeing connected to the other of said pick-up devices, the outputterminals of said phase-shifting networks being connected so as toprovide a signal which is the sum of the output signals of saidphase-shifting networks, and said phaseshifting networks havingphase-shift characteristics which difier from each other by saidpredetermined angle.

12. In a system for reproducing intelligence from a magnetized wirewhich is subject to arbitrary twists, a pair of magnetic structures atsubstantially the same location longitudinally on the wire and arrangedto carry mutually perpendicular components of flux from said wire, acoil wound in each of said structures and energized by the flux therein,and means for generating a signal equal to the square root of the sum ofthe squares of the signal induced in each of said coils.

13. The method of reproducing intelligence from a magnetized wire whichis subject to arbitrary twists, comprising generating a plurality ofcomponents from said flux, producing therefrom a plurality of Y signals,said signals being shifted "in-phase with respect to one another byelectrical angles which are substantially the same as the ;mecham'calangles of said componentsof said -flux, and addin said signalsvectorially.

W 14. A reproducer for magnetic recordings where the recorded signal isrecorded magnetically transversely of the recording medium comprisingapair of signal channels having input and output terminals fortransmitting signals of the same frequency to the same extent; means formodifying the phase of signals passing through one of said channelsrelative to the phase of signals passing through the other of saidchannels to apredetermined extent; means connected to said outputterminals for combining the output signals of said channels; magneticsignal pick-up devices for individually applying signals of the "samefrequency to the inputs of said channels; said pick-up devices beinglocated in the same plane, transverse to the direction of motion of therecording medium, and being angularly related with respect to each otherby an angle substantially less than one hundred and eighty degrees; andcircuit connections for producing the same output signal regardless ofthe instantaneous rotary orientation of the magnetic signal in the wire,said circuit connections comprising means for maintaining constant therelative phase angle between the signals at the output terminals of saidchannels regardless of the frequency of said signals.

15. A reproducer for magnetic recordings where the recorded signal isrecorded magnetically transversely of the recording medium comprising apair of signal channels having input and output terminals fortransmitting signals of the same frequency to the same extent; means formodifying the phase of signals passing through one of said channelsrelative to the phase of signals passing through the other of saidchannels to a predetermined extent; means connected to said outputterminals for combining the output signals of said channels; magneticsignal pick-up devices for individually applying signals of'the samefrequency to the inputs ofsaid channels; said pick-up devices beinglocated in the same plane, transverse to the direction of motion of therecording medium, and being angularly related with respect to each otherby anangle substantially less than one hundred and eighty degrees; andcircuit connections for producing the same output signal regardless ofthe instantaneous rotary orientation of the -magnetic signal in theWire, said circuit connections comprising means for maintaining asubstantially ninety degree phase angle between the signals at theoutput terminals of said channels regardless of the frequency of saidsignals.

16. A reproducer for magnetic recordings where the recorded-signal isrecorded magnetically transversely of the recording medium comprising apair of signal channels having input and output terminals fortransmitting signals of the same frequency to the same extent; means formodifying the phase of signals passing through one of saidchannels-relative to the phase of signals passing through the other ofsaid channels to a predetermined extent; means con- 12 nected to saidoutput terminals for combining the output signals of said channels;magnetic signal pick-up devices for individually applying signals of thesame frequency to the inputs of said channels; said pick-up devicesbeing located in the same plane, transverse to the dire'ctionof motionof the recording medium, and being effectively ninety degrees withrespect to each other; and circuit connections for producing the sameoutput signal regardless of the instantaneous rotary orientation of themagnetic signal in the wire, said circuit connections comprising meansfor maintaining constant the relative phase angle between the signals atthe output terminals of said channels regardless of the frequency ofsaid signals.

17. In a reproducer for magnetic recordings on a wire, a pair of pick-upmagnetic structures oriented at right angles with respect to one anotherand at substantially the same location longitudinally on said wire,circuit arrangement for shifting the signal outputs of said structuressubstantially with respect to each other, said circuit arrangementincluding a first phase shifter connected to the output of one of saidstructures for shifting the signals through an angle a., and a secondphase shifter connected to the output of the other of said structuresfor shifting the signals through an angle a90, and a common outputcircuit for said phase shifters in which the resultant signals are addedvectorially.

18. In a reproducer for magnetic recording on a wire, a pair of magneticpick-up structures, one of said magnetic structures being arranged topick up one component of the signal on the wire equal to the signalwhich would be induced in one of the structures if said one of thestructures were oriented to be parallel to the magnetic axis of the wiremultiplied by the cosine of the angle of orientation of the structure tothe magnetic axis of the wire, and the other structure being arranged topick up the other component making up the signal on the Wire equal tothe signal which would be induced in oneof the structures if said one ofthe structures were oriented to be parallel to the magnetic axis of thewire multiplied by the sine of the angle of orientation of the structureto the magnetic axis of the wire, individual circuit arrangementsconnected to the output of each of said structures, said circuitarrangement shifting the phase of the output signal substantially 9Oelectrical degrees with respect to each other, and a common outputcircuit for said individual circuit arrangement for vectorially addingthe signals in each of said circuit arrangements.

HOWARD E'. TOMPKINS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,949,409 Cohen Mar. 6, 19342,251,300 Star Aug. 5, 1941 2,272,821 Roys Feb. 10, 1942 2,334,510Roberts Nov. 16, 1943

